Microlens Diffusion Plate Layout for Diffraction Noise Reduction
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Solution Overview
Problem
Microlens array structures with periodically arranged cylindrical lenses suffer from spectral diffraction noise and zero-order diffraction light, leading to uneven intensity distribution and degraded light distribution properties.
Innovation Solution
A diffusion plate with a microlens array featuring randomly varied aperture width, radius of curvature, and off-center amount of cylindrical lenses, satisfying specific variation range conditions to reduce spectral noise and zero-order diffraction light.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If cylindrical lenses with the same shape are periodically arranged in a microlens array, then the light diffusion function is achieved, but spectral diffraction noise and zero-order diffraction light are produced, degrading light distribution properties
Solution Approach 1:
The patent applies asymmetry by making the cross-sectional shapes of adjacent cylindrical lenses different. Specifically, lenses in the array have alternating cross-sectional shapes (e.g., asymmetric vs. symmetric, or different curvature radii), which breaks the periodic symmetry. This asymmetric design prevents the formation of regular diffraction patterns, thereby suppressing spectral diffraction noise and zero-order diffraction light while maintaining the light diffusion function.
2Device complexity
If cylindrical lenses with the same shape are periodically arranged, then the structure is simple and easy to manufacture, but the intensity distribution of diffusion light becomes uneven due to interference and diffraction
Solution Approach 1:
The patent applies local quality by varying the cross-sectional shape parameters (such as curvature radius or asymmetric dimensions) of individual cylindrical lenses at different positions in the array. Each lens has locally optimized characteristics that differ from its neighbors, which disrupts the uniform diffraction pattern and achieves more even intensity distribution across the diffusion field, while keeping the overall manufacturing process relatively simple.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution improves the homogeneity of intensity and light distribution properties by reducing spectral noise and zero-order diffraction light, achieving enhanced light distribution.
Implementation Method 1
a diffusion plate that diffuses incoming light to a desired direction is used for changing light diffusion properties. The diffusion plate is widely utilized in various devices, for example, a display device such as a display, a projection device such as a projector, and various lighting devices. There is a diffusion plate of a type that utilizes light refraction resulting from a surface shape of the diffusion plate to diffuse incoming light at a desired diffusion angle.
Implementation Method 2
Such a diffusion plate of a microlens array type raises a problem in that, as a result of interference of wavefronts of light from the respective microlenses, a diffraction wave due to a periodic structure of a microlens arrangement occurs, and an intensity distribution of diffusion light becomes uneven.
Data Source
AI summary
Spectral noise produced by a diffraction phenomenon of a periodic structure can be reduced to improve homogeneity of intensity of straight diffusion light, and noise of zero-order diffraction light is reduced to improve light distribution properties as well. A diffusion plate 1 of a microlens array type that emits straight diffusion light includes a base material 10, and a plurality of cylindrical lenses 21 arranged in an X direction on an X-Y plane of the base material 10 and composed of elongated convex portions or elongated concave portions extending in a Y direction. An aperture width D and a radius of curvature R in the X direction of each of the cylindrical lenses 21 are randomly varied within variation ranges defined by variation full width rates δD and δR, respectively, using a reference aperture width Dk and a reference radius of curvature Rk as references, and an off-center amount Ec of each of the cylindrical lenses 21 is randomly vaned within a variation range defined by a variation full width rate δEc, where δD, δR, and δEc satisfy Expression (1), and at least either δD or δR is not 0%.